Page 78 - Glow Insulation Product Guide

PIR (PITCHED ROOF)
Pitched Roof: Insulated above & below rafters With Quinn Therm QR
Design and Installation
Insulating a pitched roof at rafter line - to create what is usually known as a warm roof - makes full use of the building volume by making the roof space available for occupation.
Installing part of the insulation between the rafters reduces the depth of insulation required above the rafters, which reduces the load on fixings and makes installation easier.
When installing Quinn Therm QR above the rafters on warm pitched roofs consult BS 5534 Code of practice for slating and tiling (including shingles) - Annex B for guidance on calculation methods and fixings.
To minimise the risk of interstitial condensation the roof structure should be progressively more vapour open from inside to outside.
An AVCL between the insulation and the internal finish is essential. The underlay should be vapour open (vapour resistance <0.25MNs/g) but water resistant, to protect against wind-driven rain and snow.
To limit heat loss and prevent problems such as condensation, mould growth and staining occurring at cold spots in the construction, insulation should be continuous at junctions between the roof and other elements, particularly the eaves and gable.
Benefits
• Suitable
refurbishment projects.
for new build and
•Quinn Therm QR rigid insulation is well suited to use in warm roof constructions whether on new build or on refurbishment projects where the roof is to be stripped and recovered.
• Quinn Therm QR is strong enough to span the rafters and to sustained loads transferred from the roof covering.
• The low thermal conductivity enables the required U-value to be achieved with a minimum thickness of insulation, which, in turn, reduces the loads applied to fixings.
•The low emissivity facings increase the thermal resistance of the air space beneath the insulation, improving the overall thermal performance of the roof.
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